5. Undergone first 131I ablation for the T4 tumour using either Thyrogen (0.9 mg IM on 2 consecutive days) or THW stimulation. This excludes use of non-standard Thyrogen regimens (i.e., had a regimen of Thyrogen other than the standard 0.9 mg IM on 2 consecutive days or received Thyrogen in combination with THW).